The present invention relates to a system and a method for operating application software in a safety critical environment. A safety critical environment is one in which a computer software activity (process, functions, etc.) whose errors such as inadvertent or unauthorized occurrences, failure to occur when required, erroneous values, or undetected hardware failures can result in a potential hazard, or loss of predictability of system outcome. A safety critical environment is necessary for safety critical computer software components wherein an inadvertent action might be directly responsible for death, injury, occupational illness, or significant operation, or where the results of a computer action would be relied on for decisions which might cause death, injury, or a significant action. A safety critical environment is a common set of standards or understandings and is addressed in military specifications such as MIL-STD-882B, which acts in concert with software which is developed under DOD-STD-2167, and DOD-STD-2168. Additionally, the ability to review and audit the operations of the computer program, after completion of its execution, to insure compliance becomes a part of the safety critical environment.
Heretofore, special purpose computers have been designed wherein the hardware and firmware built into the system are specially made to provide all of the performance, testing and reporting requirements to provide a safety critical environment for application software.
However, as government agencies such as the Food and Drug Administration, impose safety critical standards on existing medical systems, along with the requirement to validate the software development process, and the correct performance of the software when used in a safety critical operation, there is a need for providing a safety critical environment embedded within general purpose data processing systems such as those having standard commercial operating systems such as DOS, system 7 for Macintosh, Windows, OS/2, etc. This safety critical environment would also be responsible for monitoring and verifying of correct operation to permit demonstratable evidence of application system functioning.